hw/virtio/vhost-user.c - qemu - Git at Google

 /*
  * vhost-user
  *
  * Copyright (c) 2013 Virtual Open Systems Sarl.
  *
  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  * See the COPYING file in the top-level directory.
  *
  */

 #include "hw/virtio/vhost.h"
 #include "hw/virtio/vhost-backend.h"
 #include "sysemu/char.h"
 #include "sysemu/kvm.h"
 #include "qemu/error-report.h"
 #include "qemu/sockets.h"
 #include "exec/ram_addr.h"

 #include <fcntl.h>
 #include <unistd.h>
 #include <sys/ioctl.h>
 #include <sys/socket.h>
 #include <sys/un.h>
 #include <linux/vhost.h>

 #define VHOST_MEMORY_MAX_NREGIONS    8

 typedef enum VhostUserRequest {
     VHOST_USER_NONE = 0,
     VHOST_USER_GET_FEATURES = 1,
     VHOST_USER_SET_FEATURES = 2,
     VHOST_USER_SET_OWNER = 3,
     VHOST_USER_RESET_OWNER = 4,
     VHOST_USER_SET_MEM_TABLE = 5,
     VHOST_USER_SET_LOG_BASE = 6,
     VHOST_USER_SET_LOG_FD = 7,
     VHOST_USER_SET_VRING_NUM = 8,
     VHOST_USER_SET_VRING_ADDR = 9,
     VHOST_USER_SET_VRING_BASE = 10,
     VHOST_USER_GET_VRING_BASE = 11,
     VHOST_USER_SET_VRING_KICK = 12,
     VHOST_USER_SET_VRING_CALL = 13,
     VHOST_USER_SET_VRING_ERR = 14,
     VHOST_USER_MAX
 } VhostUserRequest;

 typedef struct VhostUserMemoryRegion {
     uint64_t guest_phys_addr;
     uint64_t memory_size;
     uint64_t userspace_addr;
     uint64_t mmap_offset;
 } VhostUserMemoryRegion;

 typedef struct VhostUserMemory {
     uint32_t nregions;
     uint32_t padding;
     VhostUserMemoryRegion regions[VHOST_MEMORY_MAX_NREGIONS];
 } VhostUserMemory;

 typedef struct VhostUserMsg {
     VhostUserRequest request;

 #define VHOST_USER_VERSION_MASK     (0x3)
 #define VHOST_USER_REPLY_MASK       (0x1<<2)
     uint32_t flags;
     uint32_t size; /* the following payload size */
     union {
 #define VHOST_USER_VRING_IDX_MASK   (0xff)
 #define VHOST_USER_VRING_NOFD_MASK  (0x1<<8)
         uint64_t u64;
         struct vhost_vring_state state;
         struct vhost_vring_addr addr;
         VhostUserMemory memory;
     };
 } QEMU_PACKED VhostUserMsg;

 static VhostUserMsg m __attribute__ ((unused));
 #define VHOST_USER_HDR_SIZE (sizeof(m.request) \
                             + sizeof(m.flags) \
                             + sizeof(m.size))

 #define VHOST_USER_PAYLOAD_SIZE (sizeof(m) - VHOST_USER_HDR_SIZE)

 /* The version of the protocol we support */
 #define VHOST_USER_VERSION    (0x1)

 static bool ioeventfd_enabled(void)
 {
     return kvm_enabled() && kvm_eventfds_enabled();
 }

 static unsigned long int ioctl_to_vhost_user_request[VHOST_USER_MAX] = {
     -1,                     /* VHOST_USER_NONE */
     VHOST_GET_FEATURES,     /* VHOST_USER_GET_FEATURES */
     VHOST_SET_FEATURES,     /* VHOST_USER_SET_FEATURES */
     VHOST_SET_OWNER,        /* VHOST_USER_SET_OWNER */
     VHOST_RESET_OWNER,      /* VHOST_USER_RESET_OWNER */
     VHOST_SET_MEM_TABLE,    /* VHOST_USER_SET_MEM_TABLE */
     VHOST_SET_LOG_BASE,     /* VHOST_USER_SET_LOG_BASE */
     VHOST_SET_LOG_FD,       /* VHOST_USER_SET_LOG_FD */
     VHOST_SET_VRING_NUM,    /* VHOST_USER_SET_VRING_NUM */
     VHOST_SET_VRING_ADDR,   /* VHOST_USER_SET_VRING_ADDR */
     VHOST_SET_VRING_BASE,   /* VHOST_USER_SET_VRING_BASE */
     VHOST_GET_VRING_BASE,   /* VHOST_USER_GET_VRING_BASE */
     VHOST_SET_VRING_KICK,   /* VHOST_USER_SET_VRING_KICK */
     VHOST_SET_VRING_CALL,   /* VHOST_USER_SET_VRING_CALL */
     VHOST_SET_VRING_ERR     /* VHOST_USER_SET_VRING_ERR */
 };

 static VhostUserRequest vhost_user_request_translate(unsigned long int request)
 {
     VhostUserRequest idx;

     for (idx = 0; idx < VHOST_USER_MAX; idx++) {
         if (ioctl_to_vhost_user_request[idx] == request) {
             break;
         }
     }

     return (idx == VHOST_USER_MAX) ? VHOST_USER_NONE : idx;
 }

 static int vhost_user_read(struct vhost_dev *dev, VhostUserMsg *msg)
 {
     CharDriverState *chr = dev->opaque;
     uint8_t *p = (uint8_t *) msg;
     int r, size = VHOST_USER_HDR_SIZE;

     r = qemu_chr_fe_read_all(chr, p, size);
     if (r != size) {
         error_report("Failed to read msg header. Read %d instead of %d.", r,
                 size);
         goto fail;
     }

     /* validate received flags */
     if (msg->flags != (VHOST_USER_REPLY_MASK | VHOST_USER_VERSION)) {
         error_report("Failed to read msg header."
                 " Flags 0x%x instead of 0x%x.", msg->flags,
                 VHOST_USER_REPLY_MASK | VHOST_USER_VERSION);
         goto fail;
     }

     /* validate message size is sane */
     if (msg->size > VHOST_USER_PAYLOAD_SIZE) {
         error_report("Failed to read msg header."
                 " Size %d exceeds the maximum %zu.", msg->size,
                 VHOST_USER_PAYLOAD_SIZE);
         goto fail;
     }

     if (msg->size) {
         p += VHOST_USER_HDR_SIZE;
         size = msg->size;
         r = qemu_chr_fe_read_all(chr, p, size);
         if (r != size) {
             error_report("Failed to read msg payload."
                          " Read %d instead of %d.", r, msg->size);
             goto fail;
         }
     }

     return 0;

 fail:
     return -1;
 }

 static int vhost_user_write(struct vhost_dev *dev, VhostUserMsg *msg,
                             int *fds, int fd_num)
 {
     CharDriverState *chr = dev->opaque;
     int size = VHOST_USER_HDR_SIZE + msg->size;

     if (fd_num) {
         qemu_chr_fe_set_msgfds(chr, fds, fd_num);
     }

     return qemu_chr_fe_write_all(chr, (const uint8_t *) msg, size) == size ?
             0 : -1;
 }

 static int vhost_user_call(struct vhost_dev *dev, unsigned long int request,
         void *arg)
 {
     VhostUserMsg msg;
     VhostUserRequest msg_request;
     struct vhost_vring_file *file = 0;
     int need_reply = 0;
     int fds[VHOST_MEMORY_MAX_NREGIONS];
     int i, fd;
     size_t fd_num = 0;

     assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER);

     msg_request = vhost_user_request_translate(request);
     msg.request = msg_request;
     msg.flags = VHOST_USER_VERSION;
     msg.size = 0;

     switch (request) {
     case VHOST_GET_FEATURES:
         need_reply = 1;
         break;

     case VHOST_SET_FEATURES:
     case VHOST_SET_LOG_BASE:
         msg.u64 = *((__u64 *) arg);
         msg.size = sizeof(m.u64);
         break;

     case VHOST_SET_OWNER:
         break;

     case VHOST_RESET_OWNER:
         memcpy(&msg.state, arg, sizeof(struct vhost_vring_state));
         msg.state.index += dev->vq_index;
         msg.size = sizeof(m.state);
         break;

     case VHOST_SET_MEM_TABLE:
         for (i = 0; i < dev->mem->nregions; ++i) {
             struct vhost_memory_region *reg = dev->mem->regions + i;
             ram_addr_t ram_addr;

             assert((uintptr_t)reg->userspace_addr == reg->userspace_addr);
             qemu_ram_addr_from_host((void *)(uintptr_t)reg->userspace_addr, &ram_addr);
             fd = qemu_get_ram_fd(ram_addr);
             if (fd > 0) {
                 msg.memory.regions[fd_num].userspace_addr = reg->userspace_addr;
                 msg.memory.regions[fd_num].memory_size  = reg->memory_size;
                 msg.memory.regions[fd_num].guest_phys_addr = reg->guest_phys_addr;
                 msg.memory.regions[fd_num].mmap_offset = reg->userspace_addr -
                     (uintptr_t) qemu_get_ram_block_host_ptr(ram_addr);
                 assert(fd_num < VHOST_MEMORY_MAX_NREGIONS);
                 fds[fd_num++] = fd;
             }
         }

         msg.memory.nregions = fd_num;

         if (!fd_num) {
             error_report("Failed initializing vhost-user memory map, "
                     "consider using -object memory-backend-file share=on");
             return -1;
         }

         msg.size = sizeof(m.memory.nregions);
         msg.size += sizeof(m.memory.padding);
         msg.size += fd_num * sizeof(VhostUserMemoryRegion);

         break;

     case VHOST_SET_LOG_FD:
         fds[fd_num++] = *((int *) arg);
         break;

     case VHOST_SET_VRING_NUM:
     case VHOST_SET_VRING_BASE:
         memcpy(&msg.state, arg, sizeof(struct vhost_vring_state));
         msg.state.index += dev->vq_index;
         msg.size = sizeof(m.state);
         break;

     case VHOST_GET_VRING_BASE:
         memcpy(&msg.state, arg, sizeof(struct vhost_vring_state));
         msg.state.index += dev->vq_index;
         msg.size = sizeof(m.state);
         need_reply = 1;
         break;

     case VHOST_SET_VRING_ADDR:
         memcpy(&msg.addr, arg, sizeof(struct vhost_vring_addr));
         msg.addr.index += dev->vq_index;
         msg.size = sizeof(m.addr);
         break;

     case VHOST_SET_VRING_KICK:
     case VHOST_SET_VRING_CALL:
     case VHOST_SET_VRING_ERR:
         file = arg;
         msg.u64 = (file->index + dev->vq_index) & VHOST_USER_VRING_IDX_MASK;
         msg.size = sizeof(m.u64);
         if (ioeventfd_enabled() && file->fd > 0) {
             fds[fd_num++] = file->fd;
         } else {
             msg.u64 |= VHOST_USER_VRING_NOFD_MASK;
         }
         break;
     default:
         error_report("vhost-user trying to send unhandled ioctl");
         return -1;
         break;
     }

     if (vhost_user_write(dev, &msg, fds, fd_num) < 0) {
         return 0;
     }

     if (need_reply) {
         if (vhost_user_read(dev, &msg) < 0) {
             return 0;
         }

         if (msg_request != msg.request) {
             error_report("Received unexpected msg type."
                     " Expected %d received %d", msg_request, msg.request);
             return -1;
         }

         switch (msg_request) {
         case VHOST_USER_GET_FEATURES:
             if (msg.size != sizeof(m.u64)) {
                 error_report("Received bad msg size.");
                 return -1;
             }
             *((__u64 *) arg) = msg.u64;
             break;
         case VHOST_USER_GET_VRING_BASE:
             if (msg.size != sizeof(m.state)) {
                 error_report("Received bad msg size.");
                 return -1;
             }
             msg.state.index -= dev->vq_index;
             memcpy(arg, &msg.state, sizeof(struct vhost_vring_state));
             break;
         default:
             error_report("Received unexpected msg type.");
             return -1;
             break;
         }
     }

     return 0;
 }

 static int vhost_user_init(struct vhost_dev *dev, void *opaque)
 {
     assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER);

     dev->opaque = opaque;

     return 0;
 }

 static int vhost_user_cleanup(struct vhost_dev *dev)
 {
     assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER);

     dev->opaque = 0;

     return 0;
 }

 const VhostOps user_ops = {
         .backend_type = VHOST_BACKEND_TYPE_USER,
         .vhost_call = vhost_user_call,
         .vhost_backend_init = vhost_user_init,
         .vhost_backend_cleanup = vhost_user_cleanup
         };
	/*
	* vhost-user
	*
	* Copyright (c) 2013 Virtual Open Systems Sarl.
	*
	* This work is licensed under the terms of the GNU GPL, version 2 or later.
	* See the COPYING file in the top-level directory.
	*
	*/

	#include "hw/virtio/vhost.h"
	#include "hw/virtio/vhost-backend.h"
	#include "sysemu/char.h"
	#include "sysemu/kvm.h"
	#include "qemu/error-report.h"
	#include "qemu/sockets.h"
	#include "exec/ram_addr.h"

	#include <fcntl.h>
	#include <unistd.h>
	#include <sys/ioctl.h>
	#include <sys/socket.h>
	#include <sys/un.h>
	#include <linux/vhost.h>

	#define VHOST_MEMORY_MAX_NREGIONS 8

	typedef enum VhostUserRequest {
	VHOST_USER_NONE = 0,
	VHOST_USER_GET_FEATURES = 1,
	VHOST_USER_SET_FEATURES = 2,
	VHOST_USER_SET_OWNER = 3,
	VHOST_USER_RESET_OWNER = 4,
	VHOST_USER_SET_MEM_TABLE = 5,
	VHOST_USER_SET_LOG_BASE = 6,
	VHOST_USER_SET_LOG_FD = 7,
	VHOST_USER_SET_VRING_NUM = 8,
	VHOST_USER_SET_VRING_ADDR = 9,
	VHOST_USER_SET_VRING_BASE = 10,
	VHOST_USER_GET_VRING_BASE = 11,
	VHOST_USER_SET_VRING_KICK = 12,
	VHOST_USER_SET_VRING_CALL = 13,
	VHOST_USER_SET_VRING_ERR = 14,
	VHOST_USER_MAX
	} VhostUserRequest;

	typedef struct VhostUserMemoryRegion {
	uint64_t guest_phys_addr;
	uint64_t memory_size;
	uint64_t userspace_addr;
	uint64_t mmap_offset;
	} VhostUserMemoryRegion;

	typedef struct VhostUserMemory {
	uint32_t nregions;
	uint32_t padding;
	VhostUserMemoryRegion regions[VHOST_MEMORY_MAX_NREGIONS];
	} VhostUserMemory;

	typedef struct VhostUserMsg {
	VhostUserRequest request;

	#define VHOST_USER_VERSION_MASK (0x3)
	#define VHOST_USER_REPLY_MASK (0x1<<2)
	uint32_t flags;
	uint32_t size; /* the following payload size */
	union {
	#define VHOST_USER_VRING_IDX_MASK (0xff)
	#define VHOST_USER_VRING_NOFD_MASK (0x1<<8)
	uint64_t u64;
	struct vhost_vring_state state;
	struct vhost_vring_addr addr;
	VhostUserMemory memory;
	};
	} QEMU_PACKED VhostUserMsg;

	static VhostUserMsg m __attribute__ ((unused));
	#define VHOST_USER_HDR_SIZE (sizeof(m.request) \
	+ sizeof(m.flags) \
	+ sizeof(m.size))

	#define VHOST_USER_PAYLOAD_SIZE (sizeof(m) - VHOST_USER_HDR_SIZE)

	/* The version of the protocol we support */
	#define VHOST_USER_VERSION (0x1)

	static bool ioeventfd_enabled(void)
	{
	return kvm_enabled() && kvm_eventfds_enabled();
	}

	static unsigned long int ioctl_to_vhost_user_request[VHOST_USER_MAX] = {
	-1, /* VHOST_USER_NONE */
	VHOST_GET_FEATURES, /* VHOST_USER_GET_FEATURES */
	VHOST_SET_FEATURES, /* VHOST_USER_SET_FEATURES */
	VHOST_SET_OWNER, /* VHOST_USER_SET_OWNER */
	VHOST_RESET_OWNER, /* VHOST_USER_RESET_OWNER */
	VHOST_SET_MEM_TABLE, /* VHOST_USER_SET_MEM_TABLE */
	VHOST_SET_LOG_BASE, /* VHOST_USER_SET_LOG_BASE */
	VHOST_SET_LOG_FD, /* VHOST_USER_SET_LOG_FD */
	VHOST_SET_VRING_NUM, /* VHOST_USER_SET_VRING_NUM */
	VHOST_SET_VRING_ADDR, /* VHOST_USER_SET_VRING_ADDR */
	VHOST_SET_VRING_BASE, /* VHOST_USER_SET_VRING_BASE */
	VHOST_GET_VRING_BASE, /* VHOST_USER_GET_VRING_BASE */
	VHOST_SET_VRING_KICK, /* VHOST_USER_SET_VRING_KICK */
	VHOST_SET_VRING_CALL, /* VHOST_USER_SET_VRING_CALL */
	VHOST_SET_VRING_ERR /* VHOST_USER_SET_VRING_ERR */
	};

	static VhostUserRequest vhost_user_request_translate(unsigned long int request)
	{
	VhostUserRequest idx;

	for (idx = 0; idx < VHOST_USER_MAX; idx++) {
	if (ioctl_to_vhost_user_request[idx] == request) {
	break;
	}
	}

	return (idx == VHOST_USER_MAX) ? VHOST_USER_NONE : idx;
	}

	static int vhost_user_read(struct vhost_dev dev, VhostUserMsg msg)
	{
	CharDriverState *chr = dev->opaque;
	uint8_t p = (uint8_t ) msg;
	int r, size = VHOST_USER_HDR_SIZE;

	r = qemu_chr_fe_read_all(chr, p, size);
	if (r != size) {
	error_report("Failed to read msg header. Read %d instead of %d.", r,
	size);
	goto fail;
	}

	/* validate received flags */
	if (msg->flags != (VHOST_USER_REPLY_MASK \| VHOST_USER_VERSION)) {
	error_report("Failed to read msg header."
	" Flags 0x%x instead of 0x%x.", msg->flags,
	VHOST_USER_REPLY_MASK \| VHOST_USER_VERSION);
	goto fail;
	}

	/* validate message size is sane */
	if (msg->size > VHOST_USER_PAYLOAD_SIZE) {
	error_report("Failed to read msg header."
	" Size %d exceeds the maximum %zu.", msg->size,
	VHOST_USER_PAYLOAD_SIZE);
	goto fail;
	}

	if (msg->size) {
	p += VHOST_USER_HDR_SIZE;
	size = msg->size;
	r = qemu_chr_fe_read_all(chr, p, size);
	if (r != size) {
	error_report("Failed to read msg payload."
	" Read %d instead of %d.", r, msg->size);
	goto fail;
	}
	}

	return 0;

	fail:
	return -1;
	}

	static int vhost_user_write(struct vhost_dev dev, VhostUserMsg msg,
	int *fds, int fd_num)
	{
	CharDriverState *chr = dev->opaque;
	int size = VHOST_USER_HDR_SIZE + msg->size;

	if (fd_num) {
	qemu_chr_fe_set_msgfds(chr, fds, fd_num);
	}

	return qemu_chr_fe_write_all(chr, (const uint8_t *) msg, size) == size ?
	0 : -1;
	}

	static int vhost_user_call(struct vhost_dev *dev, unsigned long int request,
	void *arg)
	{
	VhostUserMsg msg;
	VhostUserRequest msg_request;
	struct vhost_vring_file *file = 0;
	int need_reply = 0;
	int fds[VHOST_MEMORY_MAX_NREGIONS];
	int i, fd;
	size_t fd_num = 0;

	assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER);

	msg_request = vhost_user_request_translate(request);
	msg.request = msg_request;
	msg.flags = VHOST_USER_VERSION;
	msg.size = 0;

	switch (request) {
	case VHOST_GET_FEATURES:
	need_reply = 1;
	break;

	case VHOST_SET_FEATURES:
	case VHOST_SET_LOG_BASE:
	msg.u64 = ((__u64 ) arg);
	msg.size = sizeof(m.u64);
	break;

	case VHOST_SET_OWNER:
	break;

	case VHOST_RESET_OWNER:
	memcpy(&msg.state, arg, sizeof(struct vhost_vring_state));
	msg.state.index += dev->vq_index;
	msg.size = sizeof(m.state);
	break;

	case VHOST_SET_MEM_TABLE:
	for (i = 0; i < dev->mem->nregions; ++i) {
	struct vhost_memory_region *reg = dev->mem->regions + i;
	ram_addr_t ram_addr;

	assert((uintptr_t)reg->userspace_addr == reg->userspace_addr);
	qemu_ram_addr_from_host((void *)(uintptr_t)reg->userspace_addr, &ram_addr);
	fd = qemu_get_ram_fd(ram_addr);
	if (fd > 0) {
	msg.memory.regions[fd_num].userspace_addr = reg->userspace_addr;
	msg.memory.regions[fd_num].memory_size = reg->memory_size;
	msg.memory.regions[fd_num].guest_phys_addr = reg->guest_phys_addr;
	msg.memory.regions[fd_num].mmap_offset = reg->userspace_addr -
	(uintptr_t) qemu_get_ram_block_host_ptr(ram_addr);
	assert(fd_num < VHOST_MEMORY_MAX_NREGIONS);
	fds[fd_num++] = fd;
	}
	}

	msg.memory.nregions = fd_num;

	if (!fd_num) {
	error_report("Failed initializing vhost-user memory map, "
	"consider using -object memory-backend-file share=on");
	return -1;
	}

	msg.size = sizeof(m.memory.nregions);
	msg.size += sizeof(m.memory.padding);
	msg.size += fd_num * sizeof(VhostUserMemoryRegion);

	break;

	case VHOST_SET_LOG_FD:
	fds[fd_num++] = ((int ) arg);
	break;

	case VHOST_SET_VRING_NUM:
	case VHOST_SET_VRING_BASE:
	memcpy(&msg.state, arg, sizeof(struct vhost_vring_state));
	msg.state.index += dev->vq_index;
	msg.size = sizeof(m.state);
	break;

	case VHOST_GET_VRING_BASE:
	memcpy(&msg.state, arg, sizeof(struct vhost_vring_state));
	msg.state.index += dev->vq_index;
	msg.size = sizeof(m.state);
	need_reply = 1;
	break;

	case VHOST_SET_VRING_ADDR:
	memcpy(&msg.addr, arg, sizeof(struct vhost_vring_addr));
	msg.addr.index += dev->vq_index;
	msg.size = sizeof(m.addr);
	break;

	case VHOST_SET_VRING_KICK:
	case VHOST_SET_VRING_CALL:
	case VHOST_SET_VRING_ERR:
	file = arg;
	msg.u64 = (file->index + dev->vq_index) & VHOST_USER_VRING_IDX_MASK;
	msg.size = sizeof(m.u64);
	if (ioeventfd_enabled() && file->fd > 0) {
	fds[fd_num++] = file->fd;
	} else {
	msg.u64 \|= VHOST_USER_VRING_NOFD_MASK;
	}
	break;
	default:
	error_report("vhost-user trying to send unhandled ioctl");
	return -1;
	break;
	}

	if (vhost_user_write(dev, &msg, fds, fd_num) < 0) {
	return 0;
	}

	if (need_reply) {
	if (vhost_user_read(dev, &msg) < 0) {
	return 0;
	}

	if (msg_request != msg.request) {
	error_report("Received unexpected msg type."
	" Expected %d received %d", msg_request, msg.request);
	return -1;
	}

	switch (msg_request) {
	case VHOST_USER_GET_FEATURES:
	if (msg.size != sizeof(m.u64)) {
	error_report("Received bad msg size.");
	return -1;
	}
	((__u64 ) arg) = msg.u64;
	break;
	case VHOST_USER_GET_VRING_BASE:
	if (msg.size != sizeof(m.state)) {
	error_report("Received bad msg size.");
	return -1;
	}
	msg.state.index -= dev->vq_index;
	memcpy(arg, &msg.state, sizeof(struct vhost_vring_state));
	break;
	default:
	error_report("Received unexpected msg type.");
	return -1;
	break;
	}
	}

	return 0;
	}

	static int vhost_user_init(struct vhost_dev dev, void opaque)
	{
	assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER);

	dev->opaque = opaque;

	return 0;
	}

	static int vhost_user_cleanup(struct vhost_dev *dev)
	{
	assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER);

	dev->opaque = 0;

	return 0;
	}

	const VhostOps user_ops = {
	.backend_type = VHOST_BACKEND_TYPE_USER,
	.vhost_call = vhost_user_call,
	.vhost_backend_init = vhost_user_init,
	.vhost_backend_cleanup = vhost_user_cleanup
	};